EE eng. advice pls on furnace blower OEM replacement

[Steve_S]

I tried to have an elec. motor shop provide a replacement for the original furnace fan blower motor after I removed it. A new aftermarket motor worked fine on bench tests (3 speeds) but when installed would not draw any contact voltage from the control panel. Several HVAC shops (similar practice as auto dealer shops) would only discuss a manufacturer's (Carrier) replacement to the tune of $500 - $700 ($150 motor rest is R&R sheet metal labor).

I gave up and reinstalled a Carrier motor and it works fine of course. So, while I am happily and comfortably back in operation, the technical side of me seeks an explanation of what kind of circuitry in the motor signals the furnace logic board to not provide any voltage. Manufacturer''s Technical Support is buried beneath numerous layers of non-technical  "Customer support" and unavailable for discussion.

Manufacturer's certified HVAC people I have spoken with are similar to dealer auto support - e.g. replace OEM parts from a flat rate manual only. None have an electrical engineering background. The electric motor shop is similarly at a loss as to why the replacement won't work and I look forward to sharing any answer with them for our mutual enlightenment.

TIA

[walker]

I have never heard of a non OEM replacement blower motor not working.  What you described sounds like sorcery to me.  I pretty much only ever replace Carrier blowers with an after market non OEM motor, never had an issue, as long as the RPM, Voltage, Amp draw are relatively the same you should not have any issues.

[slo-115]

Sounds like the after market motor was wired incorrectly, perhaps a poor neutral connection, or plugged into a "spare" terminal and not the "high ac speed"  likely a fluke the official carrier motor worked ok. Did you test the board for adequate and correct voltage before condemning the rescue motor. Assuming your playing with a standard 1/2 or 1/3hp psc motor...........  then again I'm no engineer